Apparatus for producing substantially pure magnesium



Feb. 4, 1936. F. HANSGIRG 2,029,921

APPARATUS FOR PRODUCING SUBSTANTIALLY PURE MAGNESIUM Original Filed Feb. 3, 1933 3 SheetsrSheet 1 g z 5 T2 IN VENTO 2 a; 4.

Feb. 4, 1936. F. HANSGIRG 2,029,921

APPARATUS FOR PRODUCING SUBSTANTIALLY PURE MAGNESIUM Original Filed Feb. 3, 1933 3 Sheets-Sheet 2 F ig. 2

cooling medium.

Feb. 4, 1936. F, HAN 2,029,921

APPARATUS FOR PRODUCING SUBSTANTIALLY PURE MAGNESIUM Original Filed Feb. 5, 1933 3 Sheets-Sheet 3 Fig.3

9 cooling medium inert gas 5 5 INVENTOQ z'neri'gas f4 2 "fa lac/(chamber 446 Patented Feb. 4, 1936 UNITED STATES APPARATUS FOR PRODUCING SUBSTAN- TIALLY PURE MAGNESIUM Fritz Hansgirg, Radenthein, Carinthia, Austria,

assignor to American Magnesium Metals Corporation, Pittsburgh, Pa., a corporation of Delaware Original application February 3, 1933, Serial No. 655,067. Divided and this application October 13, 1933, Serial No. 693,470. In Austria February 11, 1932 Claims. (Cl. 266-19) This invention is a division of my application Serial No. 655,067, filed February 3, 1933, for a process of and apparatus for producing substantially pure magnesium.

Like all solid substances having a considerable vapor tension even below their melting point, metallic magnesium displays the tendency to pass directly from the condition of vapor into the solid state, without the occurrence of a liquid phase. It has therefore been repeatedly recommended to purify magnesium by sublimation, or to produce it in crystalline form, from magnesium containing originating materials, a process which, however, is attended inter alia, with the drawback, in operating on a technical scale, that it can only be performed in a periodic manner. On

the other hand, the distillation of magnesium has hitherto encountered serious difficulties.

One object of the present invention is to separate substantially pure magnesium from nonvolatile concomitant substances.

Another object of my invention is to enable magnesium to be distilled so as to condense the distillate as a liquid deposit.

A further object of the invention is to provide an apparatus for the distillation of material containing metallic magnesium which can be carried on continuously.

The process described and claimed in my application Serial No. 655,067 comprises passing crude metallic magnesium or material high in magnesium, continuously through a heated zone, in order to heat it to a temperature above the melting point, and preferably in the neighbourhood of the boiling point of magnesium, the disengaged vapors being carried by an inert or reducing gas, through an interposed filter, into the condensing zone, the vapors being prevented from cooling below the solidification point of the magnesium, by being heated on their way to the condensing zone, and being thereafter suddenly cooled to condensation point. The filtratio serves to remove contaminating particles of dus from the metallic vapors. This process is performed at reduced pressures. I

While various types of apparatus might be employed for carrying out this process, a typical apparatus according to the present invention consists substantially of an externally heated distillation chamber, which is provided with a conveyor and connected, at each end, with lock chambers, through a stock vessel or collector, and also with a condenser from which the molten magnesium runs off into a collector,'for example, through a barometric outlet, a filter being interposed between the said distillation chamber and the said condenser. The still, filter, condenser, outlet and receiver are preferably housed in a common heating chamber, such as an electric radiation furnace.

In order to render the filtration process continuous, it'is advisable to employ a filter of loose, granular material, piled up loosely, between an intake and closable outlet, in the passage connecting the still chamber with the condenser.

In a preferred embodiment of apparatus for carrying out the invention, the condenser consists of a hollow body, closed below and internally cooled, and preferably with a curved bottom, said body being disposed centrally in a heated jacket, in such a manner that the incoming vapors bathe the lowest portion of the cooling surface. This cooling tube is preferably provided with a device for maintaining a liquid or gaseous cooling medium in circulation, the arrangement being such that the heat is transmitted through the outer tube to the cooling medium principally by radiation. To enable the cooling action to be accurately regulated, it is advisable to arrange said circulating device so as to be vertically adjustable. I

In'order more clearly to understand the nature of the invention, reference is made to the accom panying drawings, which illustrate diagrammatically and by way of example, an embodiment of apparatus suitable for carrying out the process of the invention.

In said drawings Fig. 1 shows a front elevation in partial section,

Fig. 2 a cross section and Fig. 3 a modified embodiment in the same manner as in Fig. l.

Like reference characters denote like parts in the several figures of the drawings.

According to the example shown in Figs. 1 and 2, the distillation chamber l is in the form of a tube, which extends through a suitableheating apparatus, such as an electric radiation furnace 2. The material to be distilled is placed in the charging hopper? and passes through the lock chamber 4-the closure members 5 and 6 coacting with leverkinto a stock vessel I, from which it is continuously fed, by means of a worm 8 or the like; into the distillation chamber I, through which the material is conveyed by means of a worm 9 or the like.

The residue falls into a collector ID, from which it is discharged through also the chamber 4 and stock vessel I, are connected with the vacuum pump by means of pipes adapted to be closed independently.

Midway along its length the distillation tube l is connected by a conduit 12 with the outer shell l3 of a condenser, the discharge pipe I4 of which dips into the receiver i5. In the bottom of the receiver l5, there is provided avalve l6. By arranging the condenser at a level more than 6 meters above the outlet level, a perfectly automatic barometric outlet device is obtained. This known arrangement can also be replaced by the known double receiver for vacuum distillation, which enables work to be carried on without interruption by reversing devices.

According to the embodiment shown in Fig. 2, the condenser consists of the cylindrical hollow vessel 11, closed below by a curved bottom and disposed upright in the centre of the heated shell 13, in such a manner that the incoming vapors bathe the lowest portion of the cooling surface.

A tube I8 is centred in the tube I! so as to leave a small intermediate space all around and allow the transmission of heat to take place principally by radiation and is cooled by means of a liquid or gaseous cooling medium, which is admitted through the tube I9 and passes away through the lateral branch IS. The whole of the circulation device is vertically adjustable in the .tube H, in order to enable the cooling action to be accurately regulated.

In order to remove accompanying dust, a filter is interposed in the pipe I 2 connecting the chamber l with the condenser I3. The filtering medium consists preferably of loose, granular material, such as sintered magnesite, disposed loose- The arrangement ly in the connecting pipe. shown in Fig. 2 has been adopted to enable the filtering medium to be replenished without interrupting the work. The filtering medium 20 is disposed in a hopper 2|, to the lower end of which is attached a tube 23, which can be closed by a valve 22 and dips into a collector 24, whilst a pipe 25, leading from a stock vessel 26, rests on the heap. On the valve 22 being opened, the entire column of material is set in motion, the active portion becoming changed. If desired, the

-valve can be left slightly open all the time, so

that the changing is continuous. Since the filtering medium is more rapidly clogged up on the intake side than on the discharge side, it is advisable to arrange that the changing of-the medium does not proceed with the same velocity on the two sides. For this purpose a deltoid member 21 is disposed, slightly eccentrically, in the hopper 2|, so that the outlet passage on the intake side of the filter is wider than the passage on the outlet side, and the medium accordingly moves more rapidly on the intake side than at the outlet.

In order to direct the flow of the magnesium vapors, they are conducted to the condenser by means of a current of inert or reducing gas, such as hydrogen. For this purpose, supply pipes 28, 29, 30, 3|, are employed, which, in the example shown, are attached at both ends of the reaction chamber I (Fig. l) and to the stock vessel 26 and outlet pipe 23 (Fig. 2) respectively.

The material tobe distilled, such as magnesium dust, furnished by the electrothermal reduction of magnesium. compounds; is heated in the heating zone to a temperature-according to the degreeof vacuum-at which the magnesium already possesses a high vapor tension, preferably to a temperature near (slightly above) boiling point. The pipe l2 leading to the condenser (Fig. 1), the filter and the shell l3 of the condenser are heated to such an extent that the internal temperature cannot fall below the solidification temperature of the magnesium. If the distillation heated portion of the casing 32, the buckets 34 are filled with magnesium containing material from a stock vessel 35 and this material is thereafter superposed by a filtering material discharged from a stock vessel 31. The outlets of each vessel are adapted to be closed by slides 36, 38 respectively. The vapors generated in the heated section of the tube 32 pass through the filtering medium and are carried off to the condenser I3 by means ,of the flushing gas admitted 1 at 39 and 40.

Instead of conveying the materialto be distilled through the distillation zone by means of a worm or bucket elevator, the process can also be carried out with the aid of other suitable known devices permitting the flow of the material under the influence of gravity (such as for instance stationary furnaces comprising a series of hearths in step relation), or by rotation of a heated tube round its long axis (such as revolving furnaces), or by stationary furnaces provided with paddleshaped conveying devices. It is only essential that the magnesium containing material pass through a heated zone so as to be brought to a temperature which causes transformation of the magnesium into the state of vapor, which temperature, of course, depends on the pressure conditions existing in the heated system, and'that, after passing through a filter, the resulting magnesium vapor is subjected to such condensation conditions that the metal will be precipitated in liquid form.

In all cases, heat-resisting special steels, free from nickel and copper, must be employed for constructing the apparatus of the present inven: tion in order to prevent contamination of the resulting magnesium.

I claim:--

1. Apparatus for the distillation of magnesium comprising a distillation chamber provided with a conveyor for moving the magnesium material through it, a condenser connected to said cham-.

ber and comprising a cooling member extending substantially vertically, means for cooling said cooling member internally, and a. jacket member surrounding said cooling member and connected to said chamber to cause the incoming vapors I to bathe the lowermost portion of said cooling ing of a hollow bodywith a curved bottom and having cooling means arranged inside, the said condenser being disposed within a jacket connected by a pipe line to the distillation chamber andopening into a receiver for the distillate; and means for heating the distillation chamber, the jacket of the condenser, and the connecting pipes.

4. Apparatus for the distillation of magnesium comprising a distillation chamber provided with means for conveying the magnesium material through the said chamber; a condenser consisting of a hollow body having a device for the circulation of a cooling medium adjustably inserted inside, the said condenser being disposed within a jacket connected by a pipe line to the distillation chamber and opening into a receiver for the distillate; and means for heating the distillation chamber, the jacket of the condenser and the connecting pipes.

5. Apparatus for the distillation ofmagnesium comprising a distillation chamber provided with means for conveying the magnesium material through the said chamber; a condenser consisting of a hollow body having a device for the circulation of a cooling medium adjustably inserted inside, the said condenser being disposed within a jacket connected by a pipe line to the distillation chamber and opening into a receiver for the distillate; and a heating casing for housing the distillation chamber, the jacket of the condenser and the connecting pipes.

6. Apparatus for the distillation of magnesium comprising a distillation chamber provided with means for conveying the magnesium material through the said chamber; a condenser consisting of a hollow body having a device for the circulation of a cooling medium adjustably inserted inside, the said condenser being disposed within a jacket connected by a pipe line to the distillation chamber and opening into a receiver for the distillat a dust separating device interposed between the distillation chamber and the condenser: and a heating casing for housing the distillation chamber, the jacket of the condenser. the dust separating device and the connecting pipes.

7. Apparatus for refining magnesium comprising a heating chamber provided with a conveyor for moving the magnesium material through it and with locking means for inserting the material to be refined into the heating chamber and for removing the residue of treatment from said chamber; a condenser consisting of a hollow body having a device for the circulation of a cooling medium adjustably inserted inside, the said-condenser being disposed within a jacket connected by a pipe. line to the distillation chamber and opening into a receiver for the distillate; means for heating the distillation chamber, the jacket having a device for the circulation of a cooling medium adjustably inserted inside, the said condenser being disposed within a jacket connected by a pipe line to the distillation chamber and opening into a receiver for the distillate; a dust separating device interposed between the heating chamber and the condenser; a heating casing for housing the heating chamber, the jacket of the condenser, the dust separating device and the connecting pipes; and a vacuum pump and a pipe connecting said pump and the system for maintaining the system under vacuum.

9. Apparatus for refining impure magnesium comprising a heating chamber, a conveyor for moving the material to be refined through the said chamber, a condenser opening into a receiver ior the condensed product of treatment, a pipe line for conveying vapor from the heating chamher to the said condenser, and a filtering device consisting oi loosely piled sintered magnesite interposed into said pipe line.

10. Apparatus for refining impure magnesium comprising a heating chamber, a conveyor for moving the material to be refined through the said chamber, a condenser opening into a receiver for the condensed product of treatment, a pipe line for conveying vapor from the heating chamber to the said condenser, a filtering device consisting oi loosely piled sintered magnesite interposed into said pipe line, and an adjustable inset member disposed slightly excentrically in the outlet pipe oi the said filtering device so that the outlet passage on the intake side 0! the filtering device is wider than the passage on the outlet' side and the sintered magnesite accordingly moves more rapidly on the intake side than at the outlet.

' FRITZ HANSGIRG. 

